How much lead concentration was determined on a window sill that measured 2"x20" and yielded 60 ug?

To determine the lead concentration per square foot on the window sill, it's essential to calculate the area of the window sill first. The dimensions given are 2 inches by 20 inches.

1. Convert the dimensions from inches to feet:
   • The width of the window sill: 2 inches = 2/12 feet = 1/6 feet.

• The length of the window sill: 20 inches = 20/12 feet = 5/3 feet.

2. Calculate the area of the window sill in square feet:
   Area = Width × Length
   Area = (1/6) feet × (5/3) feet = 5/18 square feet.

3. Now, to find the lead concentration in micrograms per square foot (ug/ft²):
   The total lead measured is 60 micrograms.
   To find the concentration, you divide the total lead by the area in square feet:
   Lead concentration = Total lead / Area = 60 ug / (5/18) ft².

4. Calculating the division:

   • Dividing by a fraction is the same as multiplying by its reciprocal, so: